The report, from the Strategic Review of public transport links to the airport - a joint project between Glasgow Airport, Renfrewshire Council and Glasgow City Council - is expected to be published in the coming days.
And a train or tram link is put forward as the long-term solution, with an improved bus service between Gilmour Street and the air hub proposed as a short-term answer.
Speaking ahead of the publication of the report, Transport Minister Keith Brown said it was evidence that the decision to scrap the Glasgow Airport Rail Link was correct.
But he added he will instruct his officials to carry out further work on how a tram or train link to Central Station could be delivered.
Mr Brown said: "There is much more that can be done to improve the levels of bus accessibility to the airport, particularly linking to Paisley Gilmour Street Station, and I call on Glasgow Airport and Renfrewshire Council to work together as a matter of urgency on this.
"While the appraisal does not give us all of the answers, particularly around passenger forecasts and risks, we will now consider the proposal for a tram or train link from Glasgow Airport to the existing rail network into Glasgow Central."
Alistair Watson, executive member for Land & Environmental Services at Glasgow City Council, said something other than travel by road from the city to the airport should be introduced.
He said: "We can't, and should not, be in a position where we rely on travelling to our major airport by road. A light rail option could play a part."
It is almost four years since the previously planned £210million Glasgow Airport Rail Link was axed by SNP ministers.
Scottish Labour's infrastructure spokesman, James Kelly, said: "This is a U-turn from the SNP and comes after they spent £30m of public money to axe the original Glasgow Airport Rail Link project and sold the land off at knockdown prices."